depot/nixos/modules/services/networking/fedimintd.nix

{
  config,
  lib,
  pkgs,
  ...
}:
let
  inherit (lib)
    concatLists
    filterAttrs
    mapAttrs'
    mapAttrsToList
    mkEnableOption
    mkIf
    mkOption
    mkOverride
    mkPackageOption
    nameValuePair
    recursiveUpdate
    types
    ;

  fedimintdOpts =
    {
      config,
      lib,
      name,
      ...
    }:
    {
      options = {
        enable = mkEnableOption "fedimintd";

        package = mkPackageOption pkgs "fedimint" { };

        environment = mkOption {
          type = types.attrsOf types.str;
          description = "Extra Environment variables to pass to the fedimintd.";
          default = {
            RUST_BACKTRACE = "1";
          };
          example = {
            RUST_LOG = "info,fm=debug";
            RUST_BACKTRACE = "1";
          };
        };

        p2p = {
          openFirewall = mkOption {
            type = types.bool;
            default = true;
            description = "Opens port in firewall for fedimintd's p2p port";
          };
          port = mkOption {
            type = types.port;
            default = 8173;
            description = "Port to bind on for p2p connections from peers";
          };
          bind = mkOption {
            type = types.str;
            default = "0.0.0.0";
            description = "Address to bind on for p2p connections from peers";
          };
          url = mkOption {
            type = types.str;
            example = "fedimint://p2p.myfedimint.com:8173";
            description = ''
              Public address for p2p connections from peers
            '';
          };
        };
        api = {
          openFirewall = mkOption {
            type = types.bool;
            default = false;
            description = "Opens port in firewall for fedimintd's api port";
          };
          port = mkOption {
            type = types.port;
            default = 8174;
            description = "Port to bind on for API connections relied by the reverse proxy/tls terminator.";
          };
          bind = mkOption {
            type = types.str;
            default = "127.0.0.1";
            description = "Address to bind on for API connections relied by the reverse proxy/tls terminator.";
          };
          url = mkOption {
            type = types.str;
            description = ''
              Public URL of the API address of the reverse proxy/tls terminator. Usually starting with `wss://`.
            '';
          };
        };
        bitcoin = {
          network = mkOption {
            type = types.str;
            default = "signet";
            example = "bitcoin";
            description = "Bitcoin network to participate in.";
          };
          rpc = {
            url = mkOption {
              type = types.str;
              default = "http://127.0.0.1:38332";
              example = "signet";
              description = "Bitcoin node (bitcoind/electrum/esplora) address to connect to";
            };

            kind = mkOption {
              type = types.str;
              default = "bitcoind";
              example = "electrum";
              description = "Kind of a bitcoin node.";
            };

            secretFile = mkOption {
              type = types.nullOr types.path;
              default = null;
              description = ''
                If set the URL specified in `bitcoin.rpc.url` will get the content of this file added
                as an URL password, so `http://user@example.com` will turn into `http://user:SOMESECRET@example.com`.

                Example:

                `/etc/nix-bitcoin-secrets/bitcoin-rpcpassword-public` (for nix-bitcoin default)
              '';
            };
          };
        };

        consensus.finalityDelay = mkOption {
          type = types.ints.unsigned;
          default = 10;
          description = "Consensus peg-in finality delay.";
        };

        dataDir = mkOption {
          type = types.path;
          default = "/var/lib/fedimintd-${name}/";
          readOnly = true;
          description = ''
            Path to the data dir fedimintd will use to store its data.
            Note that due to using the DynamicUser feature of systemd, this value should not be changed
            and is set to be read only.
          '';
        };

        nginx = {
          enable = mkOption {
            type = types.bool;
            default = false;
            description = ''
              Whether to configure nginx for fedimintd
            '';
          };
          fqdn = mkOption {
            type = types.str;
            example = "api.myfedimint.com";
            description = "Public domain of the API address of the reverse proxy/tls terminator.";
          };
          path = mkOption {
            type = types.str;
            example = "/";
            default = "/ws/";
            description = "Path to host the API on and forward to the daemon's api port";
          };
          config = mkOption {
            type = types.submodule (
              recursiveUpdate (import ../web-servers/nginx/vhost-options.nix {
                inherit config lib;
              }) { }
            );
            default = { };
            description = "Overrides to the nginx vhost section for api";
          };
        };
      };
    };
in
{
  options = {
    services.fedimintd = mkOption {
      type = types.attrsOf (types.submodule fedimintdOpts);
      default = { };
      description = "Specification of one or more fedimintd instances.";
    };
  };

  config =
    let
      eachFedimintd = filterAttrs (fedimintdName: cfg: cfg.enable) config.services.fedimintd;
      eachFedimintdNginx = filterAttrs (fedimintdName: cfg: cfg.nginx.enable) eachFedimintd;
    in
    mkIf (eachFedimintd != { }) {

      networking.firewall.allowedTCPPorts = concatLists (
        mapAttrsToList (
          fedimintdName: cfg:
          (lib.optional cfg.api.openFirewall cfg.api.port ++ lib.optional cfg.p2p.openFirewall cfg.p2p.port)
        ) eachFedimintd
      );

      systemd.services = mapAttrs' (
        fedimintdName: cfg:
        (nameValuePair "fedimintd-${fedimintdName}" (
          let
            startScript = pkgs.writeShellScript "fedimintd-start" (
              (
                if cfg.bitcoin.rpc.secretFile != null then
                  ''
                    secret=$(${pkgs.coreutils}/bin/head -n 1 "${cfg.bitcoin.rpc.secretFile}")
                    prefix="''${FM_BITCOIN_RPC_URL%*@*}"  # Everything before the last '@'
                    suffix="''${FM_BITCOIN_RPC_URL##*@}"  # Everything after the last '@'
                    FM_BITCOIN_RPC_URL="''${prefix}:''${secret}@''${suffix}"
                  ''
                else
                  ""
              )
              + ''
                exec ${cfg.package}/bin/fedimintd
              ''
            );
          in
          {
            description = "Fedimint Server";
            documentation = [ "https://github.com/fedimint/fedimint/" ];
            wantedBy = [ "multi-user.target" ];
            environment = lib.mkMerge [
              {
                FM_BIND_P2P = "${cfg.p2p.bind}:${toString cfg.p2p.port}";
                FM_BIND_API = "${cfg.api.bind}:${toString cfg.api.port}";
                FM_P2P_URL = cfg.p2p.url;
                FM_API_URL = cfg.api.url;
                FM_DATA_DIR = cfg.dataDir;
                FM_BITCOIN_NETWORK = cfg.bitcoin.network;
                FM_BITCOIN_RPC_URL = cfg.bitcoin.rpc.url;
                FM_BITCOIN_RPC_KIND = cfg.bitcoin.rpc.kind;
              }
              cfg.environment
            ];
            serviceConfig = {
              DynamicUser = true;

              StateDirectory = "fedimintd-${fedimintdName}";
              StateDirectoryMode = "0700";
              ExecStart = startScript;

              Restart = "always";
              RestartSec = 10;
              StartLimitBurst = 5;
              UMask = "007";
              LimitNOFILE = "100000";

              LockPersonality = true;
              MemoryDenyWriteExecute = true;
              NoNewPrivileges = true;
              PrivateDevices = true;
              PrivateMounts = true;
              PrivateTmp = true;
              ProtectClock = true;
              ProtectControlGroups = true;
              ProtectHostname = true;
              ProtectKernelLogs = true;
              ProtectKernelModules = true;
              ProtectKernelTunables = true;
              ProtectSystem = "full";
              RestrictAddressFamilies = [
                "AF_INET"
                "AF_INET6"
              ];
              RestrictNamespaces = true;
              RestrictRealtime = true;
              SystemCallArchitectures = "native";
              SystemCallFilter = [
                "@system-service"
                "~@privileged"
              ];
            };
          }
        ))
      ) eachFedimintd;

      services.nginx.virtualHosts = mapAttrs' (
        fedimintdName: cfg:
        (nameValuePair cfg.nginx.fqdn (
          lib.mkMerge [
            cfg.nginx.config

            {
              # Note: we want by default to enable OpenSSL, but it seems anything 100 and above is
              # overriden by default value from vhost-options.nix
              enableACME = mkOverride 99 true;
              forceSSL = mkOverride 99 true;
              locations.${cfg.nginx.path} = {
                proxyPass = "http://127.0.0.1:${toString cfg.api.port}/";
                proxyWebsockets = true;
                extraConfig = ''
                  proxy_pass_header Authorization;
                '';
              };
            }
          ]
        ))
      ) eachFedimintdNginx;
    };

  meta.maintainers = with lib.maintainers; [ dpc ];
}